Various communication services exist which enable users to establish private conversations between them, over a network such as the Internet. Examples include IM (instant messaging) chat services, VoIP (Voice over Internet Protocol) services, picture messaging services, video messaging services and/or voice messaging services. In an IM chat conversation for example, a user can send a textual message to the one or more other users involved in the conversation. In a VoIP conversation (a call), a user can stream live voice and/or video to the other users in the conversation. In a picture messaging conversation, a user can send a still image to the other users in the conversation, while in a video messaging conversation a user can send a video clip, and in a voice messaging conversation a user can leave a (non-live) voice clip.
To be able to participate in such conversations, each of multiple users installs a respective instance of a communication client application on his or her respective user device (e.g. smartphone, tablet, or laptop or desktop computer). The communication client application may be implemented in any suitable executable or interpreted code, whether in the form of a stand-alone application running on an operating system, or a plug-in application to another application, or an applet running in a browser (e.g. purely in script, or using an API such as WebRTC). A communication client provided by a given communication service provider (potentially including different compatible releases of the application) defines a given communication service, with different service providers producing different applications and therefore providing separate services. For example, the IM application produced by a first service provider would provide a first IM service, while a second IM application produced by a second service provider would provide a second IM service; or the VoIP application produced by a first service provider would provide a first VoIP service, while a second VoIP application produced by a second service provider would provide a second VoIP service; and similarly for picture messaging or video messaging applications, etc. Note also that different conversation media can optionally be combined into the service provided by a given service provider, e.g. the application provided by a first service provider my enable a combination of IM chat messages, voice calling, video calling, picture messaging, video messaging and/or voice messaging to be included in the same conversation.
Typically the different services are characterised by different systems of usernames. For example, a given user is identified within the first communication service (for the purpose of being contacted by other users of the first service) by a first username that is unique amongst the usernames of the first service but not necessarily the second service, and is identified within the second service (for the purpose of being contacted by other users of the second service) by a second username that is unique within the second communication service but not necessarily the first service.
Private conversations are distinct from other, more public forms of communication such as social media feeds, in that a conversation is an exchange of communications between only a selected group of users who have been selected to take part in the conversation, with the exchange (i.e. both sent and received messages) being self-contained within that group. E.g. by contrast in a social media environment, it may be the case that the messages posted by any given user are only distributed to selected contacts, but the receiving user's feed will also collect together messages from other user's feeds, and those messages are not necessarily contained within the same group of users. Further, while the messages posted by any given user may only be distributed to the feeds of selected contacts, other messages posted by those contacts are in general distributed to the feeds of different sets of contacts which are not necessarily coincident, and there is no concept of a discrete conversation. Therefore unlike private conversations, social media feeds are not self-contained but rather span out in a web or mesh of contacts. Conversations also typically are conducted between smaller groups of users, e.g. less than ten users, less than five users or even just two or three users. Furthermore, usually each participant in a conversation knows who each of the other participants are, and the participants list may be displayed in the presentation of the conversation. Messages sent within a conversation are therefore directed towards specific and known participants and not accessible outside of that group or outside of the conversational context.
Communication systems that support conversations may also store unique identifiers for conversations. For example, each conversation may have its own ID and records of who the participants are, when the conversation was created and sometimes if there is an administrator with special permissions to add or delete participants to a conversation and change the name of the conversation.
Conversations allow items of content to be shared within the conversation, and nowadays may include multimedia content items such as still images, video images and/or audio clips. For example, a picture messaging application allows users to share still images amongst one another, or an IM application may allow a user to insert a picture or video into the conversation to be shared with the other users (e.g. by dragging and dropping the image into the a conversation window of the application).
In some applications, there is no restriction on the use of the shared content at the receive side. This means that any receiving user is free to save the content or share the content outside of the conversation, e.g. to share into a different conversation with different users, or even to share into a different communication service such as a social media site.
On the other hand, as a conversation may be between a small closed group of close contacts, there can be user expectations that content shared in the private conversation remains private within the conversation.
More recently, to address this concern, communication applications have been produced which “sandbox” the content they receive as part of a particular conversation. This means that any receiving user of a conversation can only view (or play out) the content through the particular client application through which that conversation was conducted, within the context of that conversation, and is blocked from saving the content or sharing it onwards to any other conversations or any other communications services—i.e. confining the content to the particular service and conversation through which it was initially shared by the source user. For example, in a sandboxed picture messaging service, a picture is only viewable through the corresponding picture messaging application through which it was received, and only in the context of the same conversation. Short of a screen capture or photographing the screen, the receiving user cannot save the image or move it in any other way outside of the conversation and application in question.